Process of electric welding.



L. S. LACHMAN.

PROCESS 0F ELEGTMC WELDING.

Patented Nov. 24, 1908,

A E 6,. o m u I m 1 ESQGM m nw. M i M gw.

vwl/1471111111110 APPLIUATI-ON FILED MAY 8, 1907. BENEWED APR. 23, 1908.904,881.

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LAURENCE s. LACHMAN, or NEW Yoan, N. Y.

PROCESS F ELECTRIC WELDING.

Specification of Letters Patent.

Application filed May 8, 1907,`Serial No. 372,504. Renewed April 23,1908. Serial No. 428,788.

fo all whom it may concern.'

` Be it known that l, LAURENCE S. LACH- MAN, a citizen of the UnitedStates, residing at New York, in the borough of Manhattan, county andState of New York, have in- --vented certain new and useful Improvementsin a Process of Electric Welding; and l do hereby declare the followingto be a full, clear, and exact description of the same, such as willenable others skilled in the art to which it appertains to make and usethe same.

This invention relates to processes of electric welding and consists ina method of forming autogenous spot welds between pieces of metal bymeans of welding currents passed through localized areas of such pieces;all .as more fully hereinafter set forth and as claimed.

l`n the prior art-,I many attempts have been made to unite metals byelectric welding but this has substantially only proved feasiblewherethe articles or pieces of metal to be welded have been of comparativelysmall scross-section, as in butt-weldiiig rods and wires; that is,uniting rods or wires end to end; or where, as in prior applicationstiled by me, special measures'are taken to localize and limit the areaof electric contact and of the-weld. Where the objects to be united arecomparatively large and have relatively large abutting orcontactingsurfaces it is practically impossible to pass sufficientcurrent to unite them in a manner analogous to this butt welding; thatis to unite them by a large-area weld between abutting surfaces.vFurther, when the objects are of comparatively little volume whilehaving comparatively large surface, as in the case of sheet .metalobjects, .suoli heavy currents as are necessary to effect large areawelds are detrimental to the metal.

in the present invention, in lieu o f attempting to weld the entireabutting surfaces of two metal objects, as in the prior art, l unitesuch surfaces by a spot weld, securingl the two objects together at onepoint. These spot welds l secure by passing the welding current throughthe two objects in a localized contacta-rea of .comparatively smalldimensions and comparatively high resistance: ln the present embodimentof my inyention, spot Weldsare secured by locally increasing theresistance of the metal at thel point of int-ended union by perforatingone orboth of the pieces of metal at this point and-iisingan electrodeterminal of somewhat larger, diameter than'theperforation and adapted to'overlap the margin of such perforation. On 'Y the current, so to speak,fans out laterally somewhat. As the heating due to imperfect Contact ofpole and metal is also at the surface, andthis may be and Very likely iseven greater than the true resistance heating, the sum of the resnlts isthat the metal atthe margin of the perforation flows into the oritice,under the pressure of the poles and because of its own fluidity, orplasticity, fills said perforation completely, if sol desired and if theoperation is properly performed, and welds itself at the saine time tothe similarly flowing metal in the orifice of the other 'body of metal,if both bodies were perforated, or to the surface of thev other body, if

the latter was imperforate. lith such an imperforate body, the metal ofthe surface" abutting on the perforation of the other body also flowsintov the perforation. The result'- 'is a spot weld, firmly andautogenouslyuniting the two bodies of metal. lf such bodies are ofcomparatively great'superficial area where joined, as in the case of twometal sheets, a pluralityof such spot welds are produced at separateisolated and properly spaced points. lf one of them is of no greatdimensions, as in the case of joining a rod to a sheet, one such spotweld may be, and usuallyis, quite suilicient.'

ln the-accompanying illustratienl` have shown, more or lessdiagrammatfcally, certain utensils and articles as used in the practiceof my. process. ln this drawing:

Figure l indicates a method of welding gether two sheets of'metall inthe manner.

above Fdescribed, both of said sheets being perforated; the ligureshowing said sheets in section placed between welding termlnals;

VFig. 2 is a similar view in which but one of the sheets is shownperforated; Fig. 3 is ariother similar View illustrating the welding ofan imperforate body of large-cross-section, sucli as a rod, to a plate,thelatter perforated; anltltig. 4e is another similar View' showiriggla,perforate sheet andan imperfol-lO suitable source of welding current; 3and 4' are two perforated plates arranged with their perforations inline. The perfor-ations 5 are somewhat smaller in diameter than are thepoles.- These latter are, as shown, preferf fably formedwith `a slightrounding off of the end. When the current is passed between the poles,the annular area of contact with the plates'forms a' spot of highresistance on either side of the plates to be joined, and an annulus ofsimilar size in line with the other annuli forms asimilar spot betweenthe two plates. And as these narrow annuli of metal forni the path forthe high amperage currents flowing from' pole to pole, they also becomehighly heated. Under the iniiuence of the heat and of the pressurefromthe rounded ends of the poles, 'the metal of the inargins is forced downinto the orifice, uniting with thatflowing in the corresponding o'riiiceof the other plate and forming a firm, permanent 'and autogenous spotweld between the two plates.

The operation with the structure of Fig. 2 is exactly the same save thatthe flowing metal of the perforated plate unites with the surface of theimperforate plate, the sur-l face metal of the latter being usuallyforced up into the perforation of the other plate to some extent.

The operation in Fig. 3 is the saine, ex cept that a hollow bar of metalreplaces the imperforate plate of Fig. 2.

In carrying out thewelding operation by the methods above described,owing to the fact that the welding terminal or terminals covering theperforation or perforations in.

` one or both of the 'objects to be welded are somewhat broader thansuch perforationsy l gether, placing said bodies of metal between andalso are slightly rounded or pointed,

A the area of contact of such terminal or terminals with the object orobjects to be welded isat first relatively small so that the heatingeffect is exceedingly great, though confined 'to the restricted regionimmediately surrounding the perforation or perforations and as the metalsoftens and spreads under the iniiuence of pressureof the terminals,

, this Contact area increases; nevertheless the area raised to weldingcondition is-usually, if not always, in` practice smaller' in diameter lthan the diameter of the weldingtermin'als,

and therefore the softened or fused metal is confinedand preventedv fromspreading out laterally, but vto the contrary is caused to spread intoand fill the perforation or perforationsg. and in like manner thegreater portion of the heat that might otherwise be radiated is-confinedto the immediate area of the weld, so that as little of the heat is thelatter being provided with a prof' 'wasted as possible. lf the metalsjoined are dissimilar metals, as forlexainplc steel to brass, the pieceperforated is that of lower conductivity, the steel in the instancecited. I can also provide a point on the metal of higher conductivitywhich will project up into the perforation of the other piece, as isshown iii Fig. 4, reference numeral (S designating a struck-upprotubcrance on plate 4.

What l claim is j l. The process ofuniting two bodies of metal by aspotweld, which consists in providing at least. one ofsuch bodies with aperforation, placing said bodies of mietal together, and passing anelectric welding current through said bodies'in the region immedia'telysurrounding 'suchperforation and 4thereby raising the temperature of theentire body of metal in such region unt-il such metal is soft .andiueiit, and 'applying pressure, and thereby causing the metal to flow"into such perforation and welding the objects together. 4

2. The process of uniting two bodies of metal by a spot weld, whichconsists in providing at least one of \`su`ch bodies witha perforation,placing said`\`bodies of metal together, placing a terminal of somewhatgreater area than said `perforation over the same and in contact withthe metal around said perforation, and passing an electric weldingcurrent through said terminal and through said bodies inthe regionimmediately surrounding such perforation and thereby raising thetemperature of the entire body of metal in such region until suoli metalis soft and fluent, and applying pres-- 3. The process of 'uniting twobodies of v met-al by a spot weld, which consists in providing at leastone of such bodies with a perforation, 4placing said bodies of metaltoterminals of greater'area than the said perforation, one of saidterminals covering said perforation,-and passing an electric weldingcurrent through said terminal and through said bodies in the Vregionimmediately surrounding sucli perforation and thereby raising thetemperature of the entire body of metal in such region until such metalis soft and fluent,and applying pres'sure,and thereby causing theinetal'to'iiow into such perforation and welding the objects together.

4. The process of uniting two' bodies of 'metal by a spot weld whichconsists in providing one such body with a perforation, placing theperforated piece of nieta-l in contact with the metal to be unitedthereto, placing a'pair of poles of somewhat greater area than saidperforation in contact with the two pieces of metal, passing a weldingcurrent between the poles and simultane- Viso placing theperforatedpieoe 'of met'al'in coni ously forcing the poles togetheruntil mar'- 1 ginal-metalows into saidv perforation 'and i unites thetwo pieces of metal Wit-han autog-f enous weld.

5. The'prooess ofY unitingftwo bodies of l metal by a spot yveldwhchconsists in proriding. one, such body, with [a perforation,

tact with'the metal to 'be united thereto, placy ingineontaetwith theedge onlyjof' thep'er-A foration tarn-electrode voffv greater `diameter'ythan ,said perforation, passing -a- 'Welding current through theelectrode and'simultanei ously ,forcing 'the electrode `and the piecesof nietal Vtogether until tlenietal on the edge kofthe* perforation Howsinto said/perforation i und unitesI the twolpieces of metal' withan inelby-a. spot' weld which consists in prol :placing the lperforfted pieceof metal 'in con- .tact 'Withthe l metal to`be united thereto,

placing inoontaotwith lthe edge only of the perforation, a pointedvelectrode the main portion of Whiehr-has a diameter greater tha-n saidperforation and the point of which enters saidperforation, soseouring'liinited initial .oontactand a high initial weldingtempernture, and .passing a 'Welding current through the electrode andbodies of n'iotal and simultaneously forcing the' electrode j andthe'pieces of metal together until. the

ing as themetal softens.

In testimony whereof I have signed'this specification in the presence oftwo subso'rihz ing witnesses. y A l l* `LAIIREY-C-E S. LACHMAN.Witnesses:`v Q vLEO J. MATTY,

H'. 4MARBrAe.

`the area of .Contact of the electrode .'euten'd-v

